Eur. Phys. J. A (2012) 48: 183
https://doi.org/10.1140/epja/i2012-12183-5

Letter

Formation of the S = -1 resonance X(2265) in the reaction pp → X+K⁺ at 2.50 and 2.85 GeV

¹ Excellence Cluster Universe, Technische Universität München, Garching, Germany
² Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, Vienna, Austria
³ Dipartimento di Fisica Generale “A. Avogadro” and INFN, Torino, Italy
⁴ Department of Physics, University of Tokyo, 113-0033, Tokyo, Japan
⁵ RIKEN Nishina Center, 351-0198, Saitama, Japan
⁶ Laboratoire National Saturne, CEA Saclay, France
⁷ Indiana University Cyclotron Facility, Bloomington, Indiana, USA
⁸ II. Physikalisches Institut, Universität Gießen, Gießen, Germany
⁹ JINR, Dubna, Russia
¹⁰ M. Smoluchowski Institute of Physics, Jagellonian University, Kraków, Poland
¹¹ H. Niewodniczanski Institute of Nuclear Physics, Kraków, Poland
¹² Università del Piemonte Orientale and INFN, Torino, Italy
¹³ Forschungszentrum Rossendorf, Rossendorf, Germany
¹⁴ INFN, Trieste, Italy

^* e-mail: ken.suzuki@oeaw.ac.at

Received: 7 June 2012
Revised: 21 October 2012
Accepted: 12 November 2012
Published online: 12 December 2012

Abstract

Analyzing DISTO data of pp → pΛK ⁺ at T ^p = 2.50 and 2.85GeV to populate a previously reported X(2265) -resonance with M ^x = 2267 MeV/c² and Γ ^x = 118 MeV at 2.85GeV, we found that the yield of X(2265) at 2.50GeV is much less than that at 2.85GeV (less than 10%), though it is expected from a kinematical consideration to be produced as much as 33% of that at 2.85GeV. The small population of X(2265) at 2.50GeV is consistent with the very weak production of Γ(1405) at the same incident energy toward its production threshold, thus indicating that Γ(1405) plays an important role as a doorway state for the formation of X(2265).